There will be tears and high emotion at the Barbican tonight when Merce Cunningham Dance Company performs for the very last time in Britain.

At the end of the year, after a two-year tour, the company will be disbanded and one of dance history’s great pioneering eras will come to an end – all exactly as its founder wanted. Under the terms of his will, Cunningham, who died in 2009 at the age of 90, left instructions for his company to be closed and replaced by a Trust that will preserve his works, allowing other companies to dance them with its permission – and providing detailed “dance capsules” of around 80 works available both for restaging and study.

It was a radical decision by a radical choreographer to try to preserve his legacy in this way. As Trevor Carlson, executive director of the Cunningham Dance Foundation, explains, Cunningham realised that if his dance company continued to run it would quickly become peopled by dancers who had never worked with him. It would then become a historic company, performing pieces that none of its personnel had any direct link with. He didn’t want that.

So instead his dancers, whom he chose and trained, will hand over their knowledge of his work to other dancers in other companies, and in the process allow the pieces to thrive. “It’s a risk,” says Carlson. “But then Merce set a brilliant example. He took risks throughout his career. And to let this powerful and significant body of work from a career that spanned an entire century disappear was unimaginable.”

The question of legacy in dance is a very vexed one. As Cunningham said: “Dancing is like water. It floats away.” Even the ballets which we regard as classics – Swan Lake, Sleeping Beauty – have sections that cannot be regarded as authentic; they have been added at later dates by many different hands. In the modern era, filming and notation have created the equivalent of texts, but these are not fixed in stone. The Cunningham Trust has discovered that there are different filmed versions of the same work in existence; and these may in turn be subtly altered from his notes.

The Cunningham Trust effectively follows the model of the George Balanchine Trust, which protects the choreographer’s works very tightly, providing former dancers to mount new versions of his ballets in approved companies around the world. It was set up a couple of years after the choreographer’s death in 1983, with money to buy back the copyrights to ballets that Balanchine had bequeathed to his friends and muses.

The Royal Ballet’s founder choreographer, Frederick Ashton, followed a similar strategy, leaving his ballets to his friends in the hope that they could make a bit of money out of them. This policy served him well when the ballets lay in the hands of the people who danced them, such as Michael Somes, Margot Fonteyn and Brian Shaw. But the death of Alexander Grant last week is a reminder of its perils: he owned La Fille mal gardée, one of Ashton’s greatest works. No one knows who will be left it in his will. Once the works pass out of the hands of dancers who understand Ashton’s legacy, they are in need of extra care.

Today, the Royal Ballet has announced the creation of the Frederick Ashton Foundation, a body that pledges to work closely with “the existing Ashton ballet copyright holders” to improve the historic understanding of Ashton’s work and develop the skills of those who will be registered to teach, coach and stage his ballets in future.

Its executive director, Christopher Nourse, says: “Ashton did make the most remarkable contribution to ballet in the 20th century and many contemporary choreographers will say he had a huge influence on them. It is not a question of preserving his works in aspic, but you have to know how to play a piano scale before you can compose in a 12-tone scale. Preserving the past is not about preventing the future – it helps to develop the future.”

Nourse is addressing the deepest question that lies behind the issue of legacy: whether works made for one time should be preserved for another. Certainly the huge availability of inherited repertory has turned ballet companies around the world into guardians of history – with all the repercussions for new works that such a shift represents.

In contemporary dance, the questions are even more acute. Cunningham’s art, though highly choreographed, was linked in part to the art scene in New York which produced a series of “happenings” – works that questioned the fundamental principles of dance by putting everyday actions on stage, or breaching conventions in other ways. Their revolutionary nature was part of their importance.

This year’s Dance Umbrella not only provides the platform for the Cunningham farewell, it also allows creators such as Lucinda Childs and Karole Armitage to recreate works that were once ground‑breaking. Armitage, who is remounting Drastic-Classicism, a signature work from 1981 that established her as the punk princess of dance, has mixed feelings about the enterprise. “How do you talk to dancers who weren’t even alive at the time about a concept such as counter-culture which really doesn’t exist any more?” she says.

Her ambivalence extends to her own legacy. “I don’t want any of my pieces preserved after I have gone,” she says. “Dance is so alive in the moment, it is about the experience of now. I think we should just accept that dance is ephemeral and let it be of its moment in the story and then go.”

Armitage Gone! Dance performs at the Southbank Centre on Tues and Wed, 0844 412 4312 or